t_sndudata(3)                                                 t_sndudata(3)




 NAME    [Toc]    [Back]
      t_sndudata() - send a data unit

 SYNOPSIS    [Toc]    [Back]
      #include <xti.h>            /* for X/OPEN Transport Interface - XTI */
      /* or */
      #include <tiuser.h>         /* for Transport Layer Interface - TLI )

      int t_sndudata(fd, unitdata);
      int fd;
      struct t_unitdata *unitdata;

 DESCRIPTION    [Toc]    [Back]
      The t_sndudata() function is used in connectionless mode to send a
      data unit to another transport user.  The argument fd identifies the
      local transport endpoint through which data is sent.  The argument
      unitdata points to a type t_unitdata structure used to specify a data
      unit being sent through the transport endpoint specified by the fd
      parameter.  The t_unitdata structure has the following members:

           struct netbuf addr;
           struct netbuf opt;
           struct netbuf udata;

      The type netbuf structure is defined in the <xti.h> or <tiuser.h>
      header file.  This structure, which is used to define buffer
      parameters, has the following members:

      unsigned int maxlen           maximum byte length of the data buffer

      unsigned int len              actual byte length of data written to
                                    buffer

      char *buf                     points to buffer location

      In unitdata, addr specifies the protocol address of the destination
      user, opt identifies protocol-specific options that the user wants
      associated with this request and udata specifies the user data to be
      sent.  The user may choose not to specify what protocol options are
      associated with the transfer by setting the len field of opt to zero.
      In this case, the provider may use default options.

      If the len field of udata is zero, and sending of zero octets is not
      supported by the underlying transport service, the t_sndudata() will
      return -1 with t_errno set to [TBADDATA].

      By default, t_sndudata() executes in the synchronous operating mode
      and may wait if flow control restrictions prevent the data from being
      accepted by the local transport provider at the time the call is made.
      However, if O_NONBLOCK is set (via t_open() or fcntl()), t_sndudata()
      will execute in asynchronous mode and will fail under such conditions.



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 t_sndudata(3)                                                 t_sndudata(3)




      The process can arrange to be notified of the clearance restriction
      via either t_look() or the EM interface.

      If the amount of data specified in udata exceeds the TSDU size as
      returned in the tsdu field of the info argument of t_open() or
      t_getinfo(), a [TBADDATA] error will be generated.  If t_sndudata() is
      called before the destination user has activated its transport
      endpoint, the data unit may be discarded.

      If it is not possible for the transport provider to immediately detect
      the conditions that cause errors [TBADADDR] and [TBADOPT], then these
      errors will alternatively be returned by t_rcvuderr().  Therefore, an
      application must be prepared to receive these errors both of these
      ways.

    Thread-Safeness    [Toc]    [Back]
      The t_sndudata() function is safe to be called by multithreaded
      applications, and it is thread-safe for both POSIX Threads and DCE
      User Threads.  It has a cancellation point.  It is neither asynccancel
 safe nor async-signal safe.  Finally, it is not fork-safe.

 RETURN VALUE    [Toc]    [Back]
      Upon successful completion, a value of 0 is returned.  Otherwise, a
      value of -1 is returned and t_errno is set to indicate the error.

 ERRORS    [Toc]    [Back]
      On failure, t_errno is set to one of the following:

      [TBADDATA]          Illegal amount of data.  Zero octets is not
                          supported.

      [TBADF]             The specified file descriptor does not refer to a
                          transport endpoint.

      [TFLOW]             Asynchronous mode is indicated because O_NONBLOCK
                          was set, but the transport provider cannot accept
                          the data because of flow-control restrictions.

      [TLOOK]             (XTI only) An asynchronous event has occurred on
                          this transport endpoint and requires immediate
                          attention.

      [TNOTSUPPORT]       This function is not supported by the underlying
                          transport provider.

      [TOUTSTATE]         (XTI only) The t_sndudata() function  was issued
                          in the wrong sequence on the transport endpoint
                          referenced by the fd parameter.

      [TSYSERR]           A system error occurred during execution of this
                          function.  A protocol error may not cause the



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 t_sndudata(3)                                                 t_sndudata(3)




                          t_sndudata() function to fail until a subsequent
                          call is made to access the transport endpoint
                          specified by the fd parameter.

      [TBADADDR]          The specified protocol address was in an incorrect
                          format or contained illegal information.

      [TBADOPT]           The specified options were in an incorrect format
                          or contained illegal information.

      [TPROTO]            This error indicates that a communication problem
                          has been detected between XTI and the transport
                          provider for which there is no other suitable XTI
                          (t_errno).

 SEE ALSO    [Toc]    [Back]
      fcntl(2), t_alloc(3), t_open(3), t_rcvudata(3), t_rcvuderr(3).

 STANDARDS CONFORMANCE    [Toc]    [Back]
      t_sndudata(): SVID2, XPG3, XPG4


 Hewlett-Packard Company            - 3 -   HP-UX 11i Version 2: August 2003